Direction finder antenna



Sept. 24, 1946. D. BELLARE DIRECTION FINDER ANTENNA Filed May 14, 1945 5Sheets-Sheet 1 INVENTOR. aqwo 'Bt L/IEE BY //4;;

A TTDRIVE Y Sept. 24, 1946. D. BELLARE 2,408,034

DmEcTIoN FINnER ANTENNA Filed May 14,, 1945 5 Sheets-Sheet 2 IN VEN TOR.DIYV/O 85M fl/FE ATmFNEY Sept. 24, 1946.

DIRECTION FINDER ANTENNA Filed may 14, 1945 5 sheets-sheet 5 A TTOIPNEYD. BELLARE 2,408,034?

Sept. 24,1946. b, BELLARE 2,408,034

DIRECTION FIKDER ANTENNA Filed May 14, 1945 s-sheets-sheet 4 IN VENTOR..

VBY iTQP/VE) Sept. 24, 1946, D; BE LARE 2,408,034

DIRECTION FINDER ANTENNA Filed May 14, 1945 5 Sheets-Sheet 5 IN V ENTOR. DAV/0 BZZ/l/FE ATTORNEY Patented Sept. 24, 1946 UNITED STATES ATENTOFFICE DIRECTION FINDER ANTENNA David Bellare, Brooklyn, N. Y., assignorto Fedoral Telephone and Radio Corporation, New York, N. Y.,acorporation of Delaware Application May 14, 1945, Serial No. 593,604

"This invention relates to improvements in direction finder antennae andmore particularly to a crossed loop wave collector used with :a sensingantenna in direction finding detection.

My invention provides certain improvements in the construction,arrangement of parts and effectiveness .of loop antennae used indirection finding systems.

An objection of this invention is to provide a novel improved antennaassembly including crossed loops, sense antenna and counterpoise, whichis especially adapted for use in connection with direction findingsystems either of a portable or fixed character.

Another object of this invention is to provide an antenna assembly ofcompact and rugged character particularly adapted for use on vehicles.

A further object of this invention is directed to "providing an antennaassembly including crossed loops, sense antenna, and counterpoise inwhich the sense antenna and counterpoise are interconnected by ashielded dummy loop network immediately adjacent thereto.

Another object of my invention is the utilization of the supportingcross arms of the loop antenna as counterpoise members for a verticalantenna.

A still further object of my invention is the provision of additionalcounterpoise members, orientation of which can be altered for initialadjustments. These additional counterpeise elements may be adjusted invertical {angle to compensate for possible directional errors.

With the foregoing and other objects in view, advantages of my inventionwill become apparent from the following description; illustrated in theaccompanying drawings wherein:

Fig. 1 is a vertical view in elevation of an antenna assembly accordingto my invention;

Fig. 2 is a top plan view of the general antenna assembly illustrated inFig. 1 i

Fig. 3 is an enlarged cross-sectional view of the upper portion of theloop antenna assembly in accordance with my invention;

Fig. 4 is an enlarged vertical view of the upper portion of the loopantenna assembly, with the Weatherproofing cover removed;

Fig. 5 is an enlarged cross-sectional'view of the junction point'ofcounterpoise and vertical sense antenna at a point 'midwav of thesupporting masty Y Fig. 6 is a View in plan of afurther embodimentloflthe invention; and

Fig.7 is a fragmentary view of a detail of Fig; 6.

8 Claims. (01. 250-33) Referring to Figs. 1 and 2, the antenna assemblyincludes a vertical supporting memberor rod 1 from the vertical midpointof which extend four radial arms 2 spaced 90 relatively to one another,and attached to therod I by an insulating connector 3, providing rigidsupport for the arms 2. The bottom of the supporting rod I is held in astrengthening support l which, in turn, is mountedfupon a generallycylindrical base member 5; The latter, in turn, may be attached to anysuitable supporting rod or antenna mounting shaft or mast. The 'fourarms Z'may be interconnected by bracing bars attached thereto bysuitable insulated clamping device l.

The crossed loop may be formed by two flexible shielded cables 6 and 9,the apices of which pass through a, top mount Ill attached to supportingrod I, the ends of which are fastened within the base'member '5 and thecentral portions of which are held by fastening devices H on the endsofthe respective arms 2. Above the top mount it may be fixed an insulatingand weatherproofing cap. l2 which supports insulator means itsurrounding the vertical sense antenna l4.

In Fig. "'3 I have shown details of the protectiing and insulating capl2 of the present invention. This combination of top mount Ill andinsulating cap 12 serves to provide support at the apices of shieldedcables 8 and 9, as well as means of support and insulation of verticalsense antenna M. The mount it consists of a tube of proper length,fiared outwardly at a 45 angle at the top. The sloping sides l5 areformed with four special openings It to receive the shielded cablesand-insulating bushings, more fully described in copending applicationsof Trevor H.

Clark, S. N. 478,081, filed March 5, 1943.

The vertical sense antenna 14 passes upward close by the apices of theloops of shielded cable 8 and 9. In order to prevent shorting, theinsulation means l3 includes an insulating bushing li mounted atthecenter of circular plate l8 on weatherproofing cap l2, with thevertical sense antenna It passing upwardly therethrough. Furtherprotection and support is provided at this point by ceramic insulatorl9.

In Fig. 4 a planview of the loop antenna shows provision for thedisplacement of cables 81 and 9 in juxtaposition with theverticalantenna I4. As an alternative it would be possible to constructthe loops in the usual manner, while mounting the verticalantennaoil-center of its base, in order to provide clearance at the .apices ofthe crossed loops. In Fig. f1 the vertical antenna I 4 crowds the twocrossed loops 8 and 9 to one side, but such a change in position ofthese portions of cables 8 and 9 does not effectually alter theconstants or characteristics of the loop antenna.

The .central portion of the loop structure, showing details ofconstruction and electrical connections, is illustrated in Fig. 5. Theradial arms 2 are supported in insulating bushings 20 and 2! composed ofa circular insulator '22, a

flanged collar 23, and a ring nut 24. The arm Z has a threaded portion25 to engage in internal threads 25 of collar 23. The arms 2 may beemployed not only as a means of support for the loop structure but alsoas a counterpoise for the sense antenna [4. Y

At the internal end of each arm 2 there is a terminal screw 21 tappedinto the end of the arm, holding a lug 28 connected in turn by lead 2 9to bolt 30 through lug 3!. Bolts 30 serve to hold in position aninsulating block 32 supported on flange la of supporting tube I.Supported on insulating block 32 is the vertical antenna l4 with athickened base 33. A bolt 34 formed integrally with base 33 is passedthrough insulating block 32 and secured by hex nut 35 which also secureslug 36. A lead 3'! from lug 36 passes through'an insulator 38 mounted onshielding can 39. The leadins 40 to a dummy loop from each of the bolts30 are brought from lugs'4l held by nut 42 through insulators 43 intothe shielding can 39. The dummy loop 44, more particularl described inthe aforementioned application of Trevor H. Clark, showing properportioning'of circuits, assumes balancing'of circuits so that theresonant frequency as determined by the capacity of the vertical antennato the radial arm counterpoise, the shielded loop and mast, the capacityof the counterpoise to the shieldedloop and mast, the internalcapacities of the windings 'of the dumm loop network, and internalshield, will be greater than the operating frequency of the loop.

The entire shielding can 39 may be suitably mounted by some means suchas shown by the flange 45 supporting an insulating base 46 held in placeby bolt 41 and nut 48. Leads 49 from thejdummy loop network 44 passthrough the insulating base 46, ending in terminals 50.

For the purposeof properly proportioning the verticalsense antenna I4 tothe counterpoise arms 2 in their resonant circuit, such vertical antennamay be so constructed as to be adjustable in length.

In order to provide means for adjustment of any additional radial armsused as counterpoise members, a system illustrated in Figs. 6 and 7 isshown, including a plurality of radial arms, some of which areadjustable in the vertical plane. Alternate arms, for example, are eachshown to include a stub for connection with extension 52 by means oftongues 53, 54, and a bolt 55.

This construction allows for orientation in the vertical angle of 180,which may be utilized to compensate for possible directional errors. Ifdesired, connecting bars like the bracing bars 6 in Fig. 2 may beincluded, but if included the adjustable arms 5!, 52 must be shortenough to clear the bars 6, or be limited in their adjustment.

.From the foregoing itwill be clear that the utilization of the fourradial supporting arms 2 as a counterpoise array for the vertical senseantenna l4 contributes to a more compact and rugged construction thanwouldbeobtainedwith described in some detail. structural details givenhave been shown by way 4. a counterpoise array supported above theloops. The rigid construction is particularly suitable for use onvehicles, and for use in areas of limited clearance.

The feature incorporated in my invention wherein the sense antenna andcounterpoise are interconnected by a shielded dummy loop networkimmediately adjacent thereto provides an assembly of maximum efiiciency,due tonegligible losses in transmission leadins.

-As will also be clear, the use of additional counterpoise members soconstructed as to be variable in orientation is a novel feature of myinvention. Simple adjustment of these additiona1 arms provides a meansof compensation'for possible directional errors.

For the sake of clarity, my invention has been of examples, and not as alimitation on the scope of my invention as set forth in the objects andaccompanying claims.

I claim:

1. A wave collector comprising a vertical supporting member a pair ofantennaloops 'positioned substantially at right angles to each other andhaving the common axis thereof in common with the vertical axis of saidmember, a plurality of arms extending radially of said member at alocation within the area of said loops, a vertical sensing antennaextending upwardly from said member from a point adjacent said arms'andmeans for coupling said. arms as a counterpoise 3. A wave collectoraccording to claim 1 wherej in at least certain of said arms includmeans for orientation of such arms in vertical planes common to thevertical axis of said supporting member.

4. A wave collector comprising a vertical supporting member, a pair ofantenna loops positioned substantially at right angles to each other andhaving the common axis thereof in common with the vertical axis of saidmember, a plurality of arms extending radially of said member to supportthe outer portions of said loops, means to insulate said arms from saidmember and said loops. a vertical sensing antenna extending upwardlyfrom said member from a point adjacent said arms, and means for couplingsaid armsas a counterpoise to said sensing antenna. 7

5. A wave collector comprising a vertical supporting member, a pair ofantenna loops positioned substantially at right angles to each other andhaving the common axis thereof in common with the vertical axis of saidmember, a plurality of arms extending radially of said member at alocation within the area of said loops, avertical However, various ofsaid arms, and means for coupling said arms as a counterpoise to saidsensing antenna.

7. A wave collector comprising a vertical supporting member, a pair ofantenna loops positioned substantially at right angles to each other andhaving the common axis thereof in common with the vertical axis of saidmember, a plurality of arms extending radially of said member anddiametrically of said loops, means to support the outer portions of saidloops from at least certain of said arms, said arms being insulated fromsaid members and said loops, a vertical sensing antenna extendingupwardly from the junction of said arms, and means for coupling saidarms as a counterpoise to said sensing antenna.

8. A wave collector comprising a, vertical supporting member, a pair ofantenna loops positioned substantially at right angles to each other andhaving the common axis thereof in common with the vertical axis of saidmember, a plurality of arms extending radially of said member at alocation within the area of said loops, means connecting certain of saidarms in insulated. relation with respect to the outer portions of saidloops to support said loops, others of said arms being provided withmeans for adjusting a part thereof laterally with respect to a planecommon to said certain arms, a vertical sensing antenna extendingupwardly from said member from a point adjacent the junction of saidarms, and means for coupling said arms as a counterpoise to said sensingantenna.

DAVID BELLARE.

